Base station device, mobile station device, control information transmission method, control information reception method and program

ABSTRACT

In a radio system which allocates resources using as units resource blocks which are formed by frequency components and time components, control information for mobile station devices, and identification information which is used to identify a format for a control information transmission channel which transmits the control information is transmitted from the base station device to the mobile station devices by means of the control information transmission channel.

CROSS-REFERENCE

This application is a continuation application of U.S. patentapplication Ser. No. 13/267,836, filed on Oct. 6, 2011, now allowed,which is a Divisional of application Ser. No. 12/551,044, filed on Aug.31, 2009, now U.S. Pat. No. 8,064,916, which is a Divisional ofapplication Ser. No. 12/522,517, filed on Jul. 8, 2009, now U.S. Pat.No. 7,904,778, which is a National Stage of International ApplicationNo. PCT/JP2008/050130, filed on Jan. 9, 2008. The InternationalApplication claims priority to Japan Patent Application No.JP2007-001801 filed on Jan. 9, 2007. The aforementioned patentapplications are hereby incorporated by reference in their entireties.

TECHNICAL FIELD

The present invention relates to a base station device, a mobile stationdevice, a control information transmission method, a control informationreception method, and a program.

Priority is claimed to Japanese Patent Application No. 2007-001801,filed Jan. 9, 2007, the contents of which are incorporated herein byreference.

BACKGROUND ART

As one method for performing 3rd generation cellular mobilecommunication, a communication standard for the W-CDMA (Wideband CodeDivision Multiple Access) scheme has been standardized by 3 GPP (3rdGeneration Partnership Project) which is an internationalstandardization project. Mobile telephone services based on thisstandard are starting up one after another in various countries. In 3GPP, examinations have been undertaken into communication technologiesknown as EUTRA (Evolved Universal Terrestrial Radio Access) and EUTRAN(Evolved Universal Terrestrial Radio Access Network) as new standardsfor this type of 3rd generation radio system. In addition, the HSDPA(High Speed Downlink Packet Access) system, which makes it possible forhigh speed packet communication in a W-CDMA system downlink to beperformed, has also been standardized.

A simple summary will now be given of the HSDPA system and of EUTRA.

In the HSDPA system, downlink physical channels include HS-PDSCH (HighSpeed Physical Downlink Shared Channel) and HS-DSCH-related SharedControl Channel HS-SCCH.

The high speed physical downlink shared channel HS-PDSCH is a sharedchannel which is shared on the downlink by a plurality of mobilestations, and is used to transmit packet data addressed to therespective mobile stations. The HS-DSCH (High Speed Downlink SharedChannel) system is included in this HS-PDSCH as a transport channel.

The HS-DSCH-related Shared Control Channel HS-SCCH is a shared channelwhich is shared on the downlink by a plurality of mobile stations, andis used to transmit information about the modulation scheme andspreading code which is required information in order for each mobilestation to demodulate the High Speed Physical Downlink Shared ChannelHS-PDSCH, information required for error correction decoding, andinformation required for a HARQ (Hybrid Automatic Repeat reQuest).

Uplink physical channels in an HSDPA system include the HS-DPCCH(Dedicated Physical Control Channel for HS-DSCH).

The High Speed Dedicated Physical Control Channel HS-DPCCH for HS-DSCHis a control channel which the respective mobile stations useindividually on the uplink, and is used to transmit downlink channeltransmission path quality information (Channel Quality Indicators; CQI)and ACK/NACK (Acknowledgement/Negative Acknowledgement) signals whichform reception confirmation information corresponding to HARQ signals.

Next, in EUTRA, an OFDM (Orthogonal Frequency Division Multiplexing)system is used for the downlink, and Adaptive Modulation and CodingScheme (AMCS) technology which is based on adaptive radio link controlsuch as channel coding and the like is used in this OFDM system. AMCS isa communication system which, in accordance with the transmission pathsituations of the respective mobile stations, switches between a varietyof radio transmission parameters such as the error correction system,the error correction code rate, the number of data modulationmulti-values, the code spreading rate of the time and frequency axes,and the multi-code multiplex number and the like in order to performhigh speed packet data transmission efficiently. For example, in datamodulation, by switching to more efficient multi-valued modulation suchas switching from QPSK (Quadri-Phase Shift keying) to 8 PSK (8 PhaseShift Keying) or 16 QAM (16 Quadrature Amplitude Modulation) as thesituation of the transmission path improves, it is possible to increasethe maximum throughput of a communication system.

Moreover, two channel arrangement systems in an OFDM system have beenproposed, namely, a Spread-OFDM system and a Non Spread-OFDM system. Ina Spread-OFDM system, a physical control channel and a physical datachannel are multiplexed on the same frequency band by means of spreadingcode multiplexing. In a Non Spread-OFDM system, a physical controlchannel and a physical data channel are multiplexed in time andfrequency by employing TDM (Time Division Multiplexing), FDM (FrequencyDivision Multiplexing), or a combination of TDM and FDM.

In EUTRA, radio frames for downlinks based on an OFDM system are dividedin a frequency direction and a time direction, and the data for eachmobile station is mapped onto each of these divided blocks. By usingmobile station identification information which identifies therespective mobile stations in order to perform this mapping, allocationinformation showing the allocation of mobile stations to each block istransmitted from the base station.

Patent Document 1: Japanese Unexamined Patent Application, FirstPublication No. 2001-237803.

Patent Document 2: Japanese Unexamined Patent Application, FirstPublication No. 2004-5297756.

DISCLOSURE OF INVENTION Problem to be Solved by the Invention

Here, in EUTRA, what type of control information should be used in orderto exchange the aforementioned allocation information used for mappingbetween the base station and the mobile stations is a significantproblem, and an efficient method for transmitting and receiving controlinformation is needed.

The present invention was conceived in view of the above describedcircumstances, and it is an object thereof to provide a base stationdevice, a mobile station device, a control information transmissionmethod, a control information reception method, and a program which makeit possible to efficiently transmit and receive control information in aradio system.

Means for Solving the Problem

According to one aspect of the present invention, there is provided abase station device in a mobile communication system, comprising thebase station device transmits to mobile station devices, by means of acontrol information transmission channel, control information for themobile station devices, and identification information which is used toidentify a format for the control information transmission channel whichtransmits the control information.

Moreover, in the above described base station device, the identificationinformation includes group identification information which identifies amobile station group which has one or a plurality of the mobile stationdevices as its component elements.

Moreover, in the above described base station device, the identificationinformation is set in accordance with a format which is predetermined inaccordance with the position within radio resources where the controlinformation transmission channel is placed.

According to another aspect of the present invention, there is provideda mobile station device in a mobile communication system, comprising themobile station device receives a signal from the base station device inwhich control information for mobile station devices, and identificationinformation which is used to identify a format for a control informationtransmission channel which transmits the control information areincluded in the control information transmission channel, and the mobilestation device acquires control information in the signal in accordancewith the identification information in the received signal.

Moreover, in the above described mobile station device, theidentification information includes group identification informationwhich identifies a mobile station group which has one or a plurality ofthe mobile station devices as its component elements.

Moreover, in the above described mobile station device, theidentification information is set in accordance with a format which ispredetermined in accordance with the position within radio resourceswhere the control information transmission channel is placed.

According to still another aspect of the present invention, there isprovided a method for transmitting control information from a basestation device to mobile station devices in a mobile communicationsystem, comprising transmitting control information for the mobilestation devices and identification information which is used to identifya format for a control information transmission channel which transmitsthe control information from the base station device to the mobilestation devices by means of the control information transmissionchannel.

According to still another aspect of the present invention, there isprovided a method for receiving control information in a mobilecommunication system in which mobile station devices receive controlinformation from a base station device, comprising receiving a signalfrom the base station device in which control information for mobilestation devices, and identification information which is used toidentify a format for a control information transmission channel whichtransmits the control information are included in the controlinformation transmission channel, and acquiring the control informationin the signal in accordance with the identification information in thereceived signal.

According to still another aspect of the present invention, there isprovided a program for use in mobile station devices in a mobilecommunication system to which resources have been allocated by a basestation device, the program causing the mobile station to execute:receiving a signal from the base station device in which controlinformation for mobile station devices, and identification informationwhich is used to identify a format for a control informationtransmission channel which transmits the control information areincluded in the control information transmission channel; and acquiringthe control information in the signal in accordance with theidentification information in the received signal.

Effect of the Invention

According to the present invention, it is possible to efficientlytransmit and receive control information in a radio system.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view showing the structure of downlink radio frames used ina radio system according to an embodiment of the present invention.

FIG. 2 is a view showing a single PRB which is expressed by anarrangement C (f, t).

FIG. 3 is a view showing a channel arrangement in a downlink when adynamic format is used.

FIG. 4 is a view showing control information which is transmitted bymeans of downlink shared control channel PSCCH.

FIG. 5 is a view showing a signal format of the downlink shared controlchannel PSCCH.

FIG. 6 is a view showing an example of resource allocation information.

FIG. 7 is a view illustrating a coding method for the downlink sharedcontrol channel PSCCH.

FIG. 8 is a view showing a signal format of the downlink shared controlchannel PSCCH which is transmitted to a semi-static format mobilestation.

FIG. 9 is a view illustrating identification information which isimparted to a CRC area of the downlink shared control channel PSCCH.

FIG. 10 is a view illustrating a group formation method for groupswithin a format.

FIG. 11 is a view showing an example in which the group formation methodfor groups within a format shown in FIG. 10(a) is applied to the signalformat of the downlink shared control channel PSCCH shown in FIG. 8(a).

FIG. 12 is a view showing an example in which the group formation methodfor groups within a format shown in FIG. 10(a) is applied to the signalformat of the downlink shared control channel PSCCH shown in FIG. 8(c).

FIG. 13 is a view showing an example in which the group formation methodfor groups within a format shown in FIG. 10(b) is applied to the signalformat of the downlink shared control channel PSCCH shown in FIG. 8(c).

FIG. 14 is a view showing an example in which the group formation methodfor groups within a format shown in FIG. 10(a) is applied to the signalformat of the downlink shared control channel PSCCH shown in FIG. 8(a).

FIG. 15 is a block diagram showing the structure of a base stationdevice.

FIG. 16 is a block diagram showing the structure of a mobile stationdevice.

FIG. 17 is a sequence diagram showing a procedure by which a basestation sets a PSCCH format for a mobile station.

FIG. 18 is a flowchart showing processing performed by a base station in1TTI.

FIG. 19 is a flowchart showing processing performed by a mobile stationin 1TTI.

REFERENCE SYMBOLS

10 Base station device

101 Data control section

102 Data modulation section

103 OFDM modulation section

104 Radio section

105 Channel estimation section

106 DFT-S-OFDM demodulation section

107 Data demodulation section

108 Control data extraction section

109 Scheduling section

109-1 DL scheduling section

109-2 UL scheduling section

110 Radio resource control section

20 Mobile station device

21 Transmitting section

22 Receiving section

201 Radio section

202 Scheduling section

203 Radio resource control section

204 Radio control section

211 Data control section

212 Data modulation section

213 DFT-S-OFDM modulation section

221 Channel estimation section

222 OFDM demodulation section

223 Data demodulation section

224 Control data extraction section

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, an embodiment of the present invention will be described indetail with reference made to the drawings.

1. Radio Frame Structure

FIG. 1 shows the structure of downlink radio frames which are used in aradio system according to the present embodiment. In FIG. 1, a downlinkradio frame is formed from blocks which are known as PRB (PhysicalResource Blocks) and which are units of radio resources which are usedin communication. A single PRB is prescribed as having a frequency widthBprb which corresponds to one or a plurality of subcarriers, and a timelength (1 sub slot) which corresponds to one or a plurality of OFDMsymbols.

Here, in FIG. 1, for the frequency axis, the frequency bandwidth B_allof the entire downlink is set at 20 MHz, the guard bandwidth is set at 2MHz, the frequency bandwidth B_prb of a single PRB is set at 180 kHz,and the frequency bandwidth B_sc of a subcarrier is set at 15 kHz. Forthe time axis, the length of a single radio frame is set at 10 ms, and aTTI (Transmission Time Interval) which is a unit transmission time(subframe) is set at 1 ms. One subframe is formed by two subslots, andone subslot is formed by seven OFDM symbols (OFDM symbols have a lengthof Ts). In this radio frame structure, a total of 2000 PRB, namely, 100in the frequency axial direction and 20 in the time axial direction arecontained in a single radio frame. Note, however, that in FIG. 1 theguard band has not been shown.

Data which is transmitted on a downlink includes: (a) user data utilizedby a user; (b) downlink control information and uplink controlinformation such as mobile station identification information (UEID—UserEquipment IDentity), modulation scheme, error correction scheme,information required for HARQ, and data length; and (c) a known pilotsignal which is used for transmission path estimation when demodulationis performed on the user data, the downlink control information, and theuplink control information. These are all mapped within each subframe.Moreover, in the leading subframe of each radio frame are also mapped:(d) synchronous signals which are used to synchronize the frames; and(e) common control information which is used to give notification aboutthe overall frame structure. In addition to these, (f) paginginformation and (g) MBMS (Multimedia Broadcast Multicast Service)information are also mapped.

Downlink physical channels which are used as channels to transmit eachof these data include downlink shared data channels PDSCH (PhysicalDownlink Shared CHannel), downlink shared control channels PSCCH(Physical Shared Control CHannel), downlink pilot channels DPICH(Downlink Pilot CHannel), synchronization channels SCH (SynchronizationChannel), common control channels CCPCH (Common Control PhysicalCHannel), paging channels PCH (Paging CHannel), and multicast channelsMCH (Multitasked Channel).

The subframes shown in FIG. 1 are subframes which transmit data tomobile station addresses, the downlink pilot channel DPICH, the downlinkshared control channel PSCCH, and the downlink shared data channel PDSCHare included in these subframes. In subslot 1 within a subframe, thedownlink pilot channel DPICH and the downlink shared control channelPSCCH are placed in the first OFDM symbol. The downlink shared controlchannel PSCCH is placed in the second and third OFDM symbols. Thedownlink shared data channel PDSCH is placed in the fourth andsubsequent OFDM symbols. In the second subslot, the downlink pilotchannel DPICH is placed in the first OFDM symbol, and the downlinkshared data channel PDSCH is placed in the second and subsequent OFDMsymbols.

The downlink pilot channel DPICH is the channel which transmits the datafor the above described (c), and is used for power measurement when cellsearch or handover is being performed, for CQI measurement in order toperform adaptive modulation, and in transmission path estimation whichis performed in order to demodulate the downlink shared control channelPSCCH and the downlink shared data channel PDSCH.

The downlink shared control channel PSCCH is the channel which transmitsthe data for the above described (b). Here, in the downlink controlinformation of the downlink shared control channel PSCCH, the PRBmodulation scheme, the data length, the position of the PRB where thedata addressed to the mobile stations is placed, and the informationrequired for the HARQ and the like are included as control informationwhich is required to demodulate user data. In the uplink controlinformation are included power control, PRB transmission timing control,the position of the PRB to which the mobile station is transmittingdata, demodulation scheme, the data length, and the ACK/NACK of the HARQfor the data transmitted by the mobile station.

The downlink shared data channel PDSCH is the channel which transmitsthe data for the above described (a), namely, the user data. When thisuser data is being demodulated, information about the modulation schemeand data length which is transmitted by the downlink shared controlchannel PSCCH is used. Moreover, in order to demodulate the downlinkshared control channel PSCCH, transmission path estimation is performedusing a pilot signal of the downlink pilot channel DPICH. Note that thedownlink shared data channel PDSCH can be shared by a plurality ofmobile stations.

FIG. 2 is a view showing a single PRB which is expressed by anarrangement C (f, t). f is the subcarrier number, and t is the OFDMsymbol number. Because the frequency bandwidth B_prb of the PRB is 180kHz, and the frequency bandwidth B_sc of the subcarrier is 15 kHz,twelve subcarriers are contained in a single PRB. Accordingly, 1≦f≦12.In addition, a single subslot is formed by seven OFDM symbols, however,this corresponds to when the OFDM symbol length Ts is a short CP (ShortCyclic Prefix) of 0.07 ms. It is also possible to extend the guardinterval length of the OFDM symbols to make a long CP. In this case, ifthe OFDM symbol length Ts is set, for example, to 0.08 ms, then six OFDMsymbols are contained in a single subslot. Accordingly, in the case of ashort CP, 1≦t≦7 while in the case of a long CP, 1≦t≦6.

In the same way as in the downlink, the uplink radio frames are alsoblocks which are made up respectively by predetermined frequency bandsand time bands, and are formed from resource blocks which are radioresource units used in communication. Hereinafter, these blocks arereferred to as PRU (Physical Resource Units). If, for example, theoverall bandwidth of the uplink (i.e., the uplink frequency bandwidth)is taken is 20 MHz, the PRU bandwidth is taken is 180 kHz, thesubcarrier frequency bandwidth Bsc is taken as 15 kHz, the length of asingle radio frame is taken as 10 ms, the user unit transmission timeTTI is taken as 1.0 ms (subframes), and the guard band is 2 MHz, then asingle radio frame is formed by 1000 PRU, namely, by 100 PRU in thefrequency axial direction and 10 PRU in the time axial direction.

2. Dynamic Format and Semi-Static Format

In the radio system of the present embodiment, each mobile stationreceives control information from the base station in either a dynamicformat or semi-static format, or in both a dynamic format and asemi-static format. Here, in the case of a dynamic format, the controlinformation is transmitted from the base station in a predeterminedchannel for each TTI (i.e., subframe). In contrast, in the case of asemi-static format, the control information is transmitted from the basestation in advance, for example, at the start of communication, and isnot transmitted for each TTI. In addition, information which isdifferent from the control information sent beforehand (such as mobilestation identification information and the like--described in detailbelow) is transmitted for each TTI. The base station designates whethereach mobile station will receive control information in dynamic formator in semi-static format.

Hereinafter, descriptions will be given of the dynamic and semi-staticformats.

2. (1) Dynamic Format

FIG. 3 shows the channel arrangement in a downlink. Here, one subframehaving a frequency width of 5 MHz is shown. One PRB has a frequencybandwidth B_prb of 180 kHz, and 25 PRB are contained within one subslotof 5 MHz width. One subframe is formed by two subslots (i.e., subslot 1and subslot 2). In the leading OFDM symbol of each subslot, the downlinkpilot channel DPICH is placed every three subcarriers, namely, C (x,1):x=2, 5, 8, 11. The downlink shared control channel PSCCH is placed inan area of the leading OFDM symbol of subslot 1 which is not used forthe downlink pilot channel DPICH, namely, in C (x, 1):x≠2, 5, 8, 11, andin the second and third OFDM symbols of subslot 1, namely, in C (x,2):x=1 to 12 and C (x, 3):x=1 to 12. The downlink shared data channelPDSCH is placed in the remaining areas of subslot 1 and subslot 2.

Resource allocation for the mobile stations is performed using thedownlink shared control channel PSCCH which was placed in the mannerdescribed above. Here, as is described above, the downlink sharedcontrol channel PSCCH is only placed in subslot 1, however, the PRB ofsubslot 1 and the PRB of subslot 2 are associated together in advance,and if the PRB of subslot 1 is designated for a mobile station by thedownlink shared control channel PSCCH which has been placed in subslot1, then because of the aforementioned association, the PRB of subslot 2is also determined automatically. Because of this, compared with whendifferent resource allocation is performed for each subslot using thedownlink shared control channel PSCCH in each subslot, the controlinformation load can be made lighter. In this manner, the resourceallocation designation for a single subframe is performed in lots of 25PRB.

FIG. 4 shows control information transmitted by the downlink sharedcontrol channel PSCCH (i.e., control information in a dynamic format).FIG. 5 shows the signal format of the downlink shared control channelPSCCH. As is described above, downlink control information or uplinkcontrol information is contained in the downlink shared control channelPSCCH.

The downlink control information is formed by the respective informationfrom three categories: Cat1, Cat2, and Cat3. Catl is used for resourceallocation and includes mobile station identification information anddownlink resource allocation information. Cat2 shows the transportformat of the downlink shared data channel PDSCH allocated to eachmobile station, and includes the modulation scheme, payload size, andMIMO (Multiple Input Multiple Output)-related information. Cat3 isinformation relating to HARQ, and includes process numbers andretransmission numbers in the case of asynchronous HARQ, andretransmission numbers in the case of synchronous HARQ.

Moreover, in the same way, the uplink control information is formed bythe respective information from three categories: Cat1, Cat2, and Cat3.Cat1 is used for resource transmission grant and includes mobile stationidentification information and resource allocation information foruplink data transmissions. Cat2 shows the transport format when therespective mobile stations are transmitting uplink data, and includesthe modulation scheme, payload size, and MIMO (Multiple Input MultipleOutput)-related information. Cat3 is information relating to HARQ, andincludes retransmission numbers due to synchronous HARQ being used inthe uplink. Furthermore, uplink time synchronization signals are alsocontained in the uplink control information. These uplink timesynchronization signals are necessary to enable synchronous processingto be performed during an uplink transmission in order for differencesbetween data arrival times which are caused by variations in thedistances between the base station and the mobile stations to beadjusted on the mobile station side.

Here, the data sizes of the respective types of information are asfollows.

The mobile station identification information is able to be identifiedwithin the base station, and uses specific 16-bit C-RNTI (Cell SpecificRadio Network Temporary Identity).

The resource allocation information for the downlink control informationuses bitmap corresponding to the number of PRB, and shows which PRB amobile station should use. Here, because there are 25 PRB (see FIG. 3),the resource allocation information requires 25 bits. FIG. 6 shows anexample of resource allocation information. In the case of this example,PRB #3 and PRB #24 are allocated.

The resource allocation information for the uplink control informationspecifies blocks which are continuous using a start block number (4bits) and an end block number (4 bits). The reason for this is that,because a single carrier transmitter is used in the uplink, it isnecessary to perform allocation in a continuous block.

The modulation scheme which is used can be any one of QPSK 1/8, QPSK1/4, QPSK 1/2, QPSK 2/3, 16 QAM 1/2, 16 QAM 2/3, 64 QAM 1/2, 64 QAM 3/5,64 QAM 2/3, and 64 QAM 3/4, and four of these are used. Accordingly, twobits are required in order to identify these four modulation schemes.

The payload size shows the information quantity of data transmitted bythe downlink shared data channel PDSCH in six bits.

The MIMO related information shows the number of antennas, the number ofstreams, and MIMO control information using two bits.

The HARQ process number is information which is used to identify theHARQ process, and three bits are required for this.

The HARQ retransmission number shows the retransmission sequence withina particular HARQ process, and is expressed in two bits.

The uplink time synchronization signal uses one bit in order to show thedifference from the current synchronization time of a mobile station.

In this manner, in a dynamic format, control information made up of atotal of 56 bits for the downlink control information or a total of 37bits for the uplink control information is transmitted using thedownlink shared control channel PSCCH. In contrast, as was illustratedusing FIG. 3, because the downlink shared control channel PSCCH isplaced in a portion of the leading OFDM symbol of a single subframe (perone PRB, subtracting from the 12 subcarriers the 4 subcarriers which areused by the downlink pilot channel DPICH) and in the second and thirdOFDM symbols, the number of subcarriers transmitting the downlink sharedcontrol channel PSCCH within the one subframe having a 5 MHz width shownin FIG. 3 is:

(12−4)×25+12×25×2=800

When these 800 subcarriers are coded, for example, using a QPSKmodulation scheme and a code rate of ⅓, then 533 bits can betransmitted.

Accordingly, in one subframe having a 5 MHz width, it is calculated thatit is possible for a maximum of five (533÷93) downlink shared controlchannels PSCCH to be contained in each of the downlink and uplink.Namely, when control information is transmitted using a dynamic format,it is possible to allocate five mobile stations to each of the downlinkand the uplink for one TTI (i.e., subframe) (for a frequency bandwidthof 5 MHz). However, it is not essential for the number of uplink controlinformation units and downlink control information units to be the same.

FIG. 7 is a view illustrating a coding method for the downlink sharedcontrol channels PSCCH. In order to code the downlink shared controlchannels PSCCH, UEID masked CRC (Cyclic Redundancy Check) is used as themobile station identification information C-RNTI for each mobilestation. In addition, the downlink shared control channels PSCCH arecoded such that the CRC bit string which is obtained by performing CRCon the data of the relevant channel is the same as the mobile stationidentification information C-RNTI.

In this manner, the coding of the downlink shared control channels PSCCHis performed individually for each mobile station in accordance with themobile station which is the destination of that transmission. The mobilestations (i.e., dynamic format mobile stations) receive all of thedownlink shared control channels PSCCH of each TTI and perform CRCthereon, and once a mobile station has obtained the same CRC bit stringas its own mobile station identification information C-RNTI, itidentifies that this downlink shared control channel PSCCH is addressedto itself, and that decoding can be performed correctly.

2. (1) Semi-Static Format

The semi-static format is a signal format for when a portion of resourceallocation information, modulation scheme, payload size, MIMO-relatedinformation, information relating to HARQ, and mobile stationidentification information and the like are transmitted at the start ofcommunication or the like and are made semi-static.

FIG. 8 shows the signal formats of downlink control information oruplink control information for a downlink shared control channel PSCCHwhich is transmitted to a semi-static format mobile station. The signalformat for a downlink shared control channel PSCCH in the case of asemi-static format can have a variety of types as is shown by (a)through (c) in FIG. 8.

FIG. 8(a) is the signal format when control information other than themobile station identification information (i.e., resource allocationinformation, modulation format, payload size, MIMO-related information,and information relating to HARQ) is transmitted at the start ofcommunication and is made semi-static. Here, Short UEID is utilized asthe mobile station identification information. Short UEID isidentification information which is used to identify each mobile stationamong a group made up of a plurality of mobile stations, and isconstructed, for example, in four bits which is shorter than the C-RNTIof the above described dynamic format. Accordingly, the number of mobilestations which can be identified using this Short UEID is 16. Short UEIDis not limited to four bits, and it is also possible to use differentbit numbers in accordance with the signal format of the PSCCH.

The format shown in FIG. 8(a) is defined as Format 1. In Format 1, onlythe Short UEID and the CRC are arranged in a downlink shared controlchannel PSCCH. Nine Short UEID fields are provided, and the position ofeach field is matched 1 to 1 with the PRB which is to be used by themobile station whose own Short UEID was specified in that field. Namely,a PRB or PRU which has been matched to a particular Short UEID field isallocated to the mobile station whose Short UEID has been specified inthat particular Short UEID field.

16-bit identification information showing Format 1 (F1-ID) is attachedto a CRC area. The identification information identifying the format ofthis downlink shared control channel PSCCH is called format ID. Bypreparing a plurality of these Fl-ID, it is possible to group togetherthe mobile stations using Format 1. By employing this method, for eachgroup of Format 1, the base station sets mobile stations whose ShortUEID is to be specified. These format IDs may also be structured suchthat different ID are allocated between the uplink control informationand the downlink control information of a downlink shared controlchannel PSCCH.

FIG. 8(b) is a signal format for when the Short UEID is used and also aportion of the control information is altered dynamically. This formatis defined as Format 2. Here, the control information which isdynamically altered is called LTFS (Limited Transport Format Set). InFIG. 8(b), the LTFS is taken as being information which it is possibleto express using 3 bits. In this case, five sets of Short UEID and LTFScan be arranged in a downlink shared control channel PSCCH. 16-bitidentification information showing Format 2 (F2-ID) is attached to a CRCarea.

FIG. 8(c) is a signal format for when Short UEID is not used and aportion of the control information is dynamically altered. This formatis defined as Format 3. 16-bit identification information showing Format3 (F3-ID) is attached to a CRC area. Because Short UEID is not used, thenumber of mobile stations which are able to use the respective LTFSfields is limited to one mobile station within a group. Because of this,associations are configured in advance between the LTFS field and themobile stations within the group using exchanges between the basestation and the mobile stations. Usage of the LTFS field is able to beconfigured for each individual mobile station. In this example, the LTFSis formed by eight bits.

By employing this type of structure, it becomes possible to share thepayload portion of a downlink shared control channel PSCCH between aplurality of formats, and it becomes possible to use a plurality offormats in the same physical channel.

FIG. 9 is a view illustrating identification information which isattached to a CRC area of a downlink shared control channel PSCCH.

FIG. 9(a) shows a relationship when a 16-bit ID is shared by the C-RNTI,the Fl-ID, the F2-ID, and the F3-ID. In a 16-bit ID, it is possible toallocate 65,536 types of ID, and these are divided between an area wherethey are used as the C-RNTI, an area where they are used as the F1-ID,an area where they are used as the F2-ID, and an area where they areused as the F3-ID. An area which is not used by the other formats isallocated for the C-RNTI to the mobile stations. Two IDs, namely, ID #1in Format 1 and ID #2 in Format 1 are allocated for IDs used as Fl-ID.As is described above, this is because a plurality of IDs to be used inFormat 1 are prepared, and these are used as group IDs to identifygroups inside a format. The plurality of mobile stations which useFormat 1 are divided into groups, and IDs in Format 1 are used for theidentification of each of these groups. In the same way, a plurality ofIDs in Format 2 and a plurality of IDs in Format 3 are prepared and areused as group IDs. These group IDs may also be structured such thatdifferent ID are allocated between the uplink control information andthe downlink control information of a downlink shared control channelPSCCH. The classification of the 16-bit ID shown in FIG. 9(a) isnotified to the mobile stations by RRC signaling or broadcastinformation. It is also possible to simply use several higher order bitsof the 16-bit ID as the format identifier. Moreover, it is also possibleto reduce the amount of information to be notified by means of RRCsignaling or broadcast information by specifying the classification inFIG. 9(a) in advance.

FIG. 9(b) shows a method in which, by performing the formatidentification described in FIG. 9(a) using physical control signalplacement, a 16-bit ID area can be efficiently utilized. Areas of thedownlink shared control channels PSCCH are grouped together, and formatidentifiers are associated with each of the PSCCH area groups. Whenthere are six downlink shared control channel PSCCH areas, then theformats which can be used in each downlink shared control channel areaare limited. For example, PSCCH #1 and PSCCH #4 are set in advance foruse by Format 1 or C-RNTI, and PSCCH #2 and PSCCH #5 are set in advancefor use by Format 2 or C-RNTI. Even if the same information string isallocated as a 16-bit ID for Format 1 and Format 2, they can beidentified by the physical placement of the control signals. Byemploying this type of method, a 16-bit ID is only used as an identifierin order to specify C-RNTI or an ID within a format, and it is possibleto reduce the identifiers which are used to specify formats. Theseassociations are notified to the mobile stations using broadcastinformation or RRC signaling.

FIG. 9(c) shows a method in which, by performing the identification ofgroups within a format described in FIG. 9(a) using physical controlsignal placement, a 16-bit ID area can be efficiently utilized. Areas ofthe downlink shared control channels PSCCH are grouped together, andidentifiers of groups within a format are associated with each of thePSCCH area groups. When there are six downlink shared control channelPSCCH areas, then the groups within a format which can be used in eachdownlink shared control channel area are limited. For example, PSCCH # 1is set in advance for use by ID #1 within a format or C-RNTI, and PSCCH#2 is set in advance for use by ID #2 within a format or C-RNTI. Even ifthe same information string is allocated as a 16-bit ID for ID #1 withina format and ID #2 within a format, they can be identified by thephysical placement of the control signals. By employing this type ofmethod, a 16-bit ID is only used as an identifier in order to specifyC-RNTI or a format, and it is possible to reduce the identifiers whichare used to specify groups within a format. These associations arenotified to the mobile stations using broadcast information or RRCsignaling.

It is also possible to use a combination of FIG. 9(b) and FIG. 9(c). Bygrouping together areas of the downlink shared control channels PSCCH,and associating a portion of the groups within a format and a portion ofthe groups with the respective PSCCH groups, it is possible toefficiently utilize the 16-bit ID areas. For example, PSCCH #1 and PSCCH#4 are set in advance for use by ID #1 to #2 within Format 1, or by ID#1 to #2 within Format 2, or by C-RNTI, and PSCCH #2 and PSCCH #5 areset in advance for use by ID #3 to #4 within Format 1, or by ID #1 to #2within Format 3, or by C-RNTI. Even if the same information string isallocated as a 16-bit ID for ID #1 within Format 2 and ID #1 withinFormat 3, they can be identified by the physical placement of thecontrol signals. These associations are notified to the mobile stationsusing broadcast information or RRC signaling.

The method used to group together the groups within the formats may be amethod in which groups within a format having different associatedphysical resources are grouped together, or a method in which groupswithin a format having different users are grouped together. FIG. 10 (a)shows groupings of PRB, with PRB group 1 containing PRB #1 through PRB#4, PRB group 2 containing PRB #5 through PRB #8, and PRB group 3containing PRB #9 through PRB #12. The PRB groups may be set so as toextend across a plurality of radio frames, or may be set in TTI units.FIG. 10(b) shows groupings of mobile stations, with UE group 1containing UE #1 through UE #4, UE group 2 containing UE #5 through UE#8, and UE group 3 containing UE #9 through UE #12. FIG. 10(c) showsgroupings made up of sets of UE groups and PRB groups, with group set 1containing PRB #1 through PRB #4 and UE #1 through UE #4, group set 2containing PRB #5 through PRB #8 and UE #5 through UE #8, and group set3 containing PRB #9 through PRB #12 and UE #9 through UE #12. Here, adescription has been given of when downlink PRB are grouped together,however the uplink PRU are also grouped together into PRU groups.

FIGS. 11 through 14 show an example in which the grouping method forgroups within formats shown in FIG. 10(a) through 10(c) is performed onthe signal format of the downlink shared control signals PSCCH shown inFIG. 8(a) through 8(c).

FIG. 11 shows a case in which FIG. 8(a) and FIG. 10(a) are combined. Inthe case of Format 1, because there is no information for resourceallocation, it is necessary to associate in advance the placement of theShort UEID with the position of the PRB or PRU. This association isidentified by the ID within the format. In this example, in the case ofID #1 within the format, the area of Short UEID #1 is associated withPRB #1 and PRB #2. In the case of ID #2 within the format, the area ofShort UEID #1 is associated with PRB #11 and PRB #12.

FIG. 12 shows a case in which FIG. 8(c) and FIG. 10(a) are combined. Inthe case of Format 3, there are instances when limited resourceallocation information is set. This limited resource allocationinformation is able to freely select a PRB within a PRB group or a PRUwithin a PRU group. The PRB which can be selected by LTFS is set as aPRB group, and the association between the PRB group and Format 3 isidentified by the ID within the format. In this example, in the case ofID #1 within the format, PRB #1 through PRB #10 can be selected by meansof LTFS. In the case of ID #2 within the format, PRB #11 through PRB #20can be selected by means of LTFS.

FIG. 13 shows a case in which FIG. 8(c) and FIG. 10(b) are combined. Inthe case of Format 3, because there is no Short UEID information, it isnecessary to associate in advance the placement of the LTFS with themobile stations. This association is identified by the ID within theformat. In this example, in the case of ID #1 within the format, thearea of LTFS #1 is associated with UE #1. In the case of ID #2 withinthe format, the area of LTFS #1 is associated with UE #6.

FIG. 14 shows a case in which FIG. 8(a) and FIG. 10(a) are combined. Inthe case of Format 1, it is possible to identify mobile stations withina UE group by means of Short UEID. This Short UEID is able to freelyselect the mobile station within a UE group. The mobile group which canbe selected by Short UEID is set as a UE group, and the associationbetween the UE group and Format 1 is identified by the ID within theformat. In this example, in the case of ID #1 within the format, UE #1through UE #6 can be selected by means of Short UEID. In the case of ID#2 within the format, UE #7 through UE #11 can be selected by means ofShort UEID.

When FIG. 9(c) and FIG. 10(a) are used simultaneously, the resourceswhich can be used by the semi-static format mobile stations which arelocated in PSCCH #1 are limited to the PRB within PRB group 1. When FIG.9(c) and FIG. 10(b) are used simultaneously, the semi-static formatmobile stations which are located in PSCCH #1 are limited solely to themobile stations within UE group 1. When FIG. 9(c) and FIG. 10(a) andFIG. 10(b) are used simultaneously, the semi-static format mobilestations which are located in PSCCH #1 are the mobile stations within UEgroup #1, and the usable resources are limited to PRB group 1.

3. Structures of the Base Station and Mobile Stations

Next, the structures of the base station device and mobile stationdevices which create the above described radio system of the presentembodiment will now be described.

FIG. 15 is a block diagram showing the structure of a base stationdevice 10. The base station device 10 is constructed so as to include adata control section 101, a data modulation section 102, an OFDMmodulation section 103, a radio section 104, a channel estimationsection 105, a DFT-S-OFDM demodulation section 106, a data demodulationsection 107, a control data extraction section 108, a scheduling section109, and a radio resource control section 110.

Transmission data transmitted to the respective mobile station devices(i.e., the mobile station device 20 shown in FIG. 16 (described below))and control data are input into the data control section 101. Based oncommands from the scheduling section 109, the data control section 101maps control data to the common control channel CCPCH, thesynchronization channel SCH, the paging channel PCH, the downlink pilotchannel DPICH, and the downlink shared control channel PSCCH, and mapstransmission data to the downlink shared data channel PDSCH. Here, thedata control section 101 has a PSCCH creation control section 1011, andthis PSCCH creation control section 1011 performs the mapping inaccordance with frequency scheduling information from the schedulingsection 109.

The data modulation section 102 performs data modulation on the data ofeach channel input from the data control section 101 in accordance withthe coding sheme and the data modulation sheme of the MCS informationinstructed by the scheduling section 109.

The OFDM modulation section 103 performs OFDM signal processing on inputsignals received from the data modulation section 102 such asserial/parallel conversion, IFFT (Inverse Fast Fourier Transform)processing, CP (Cyclic Prefix) processing, and filtering and the like soas to create an OFDM signal.

The radio section 104 upconverts data received from the OFDM modulationsection 103 to a radio frequency, and transmits this by downlink to amobile station device. The radio section 104 also receives data viauplink from mobile station devices, and down-converts the received datato a baseband signal which it then delivers to the channel estimationsection 105 and the DFT-S-OFDM demodulation section 106.

The channel estimation section 105 estimates radio transmission pathcharacteristics from uplink pilot signals which are provided by the datainput from the radio section 104, and delivers the estimation results tothe DFT-S-OFDM demodulation section 106 and the scheduling section 109

The DFT-S-OFDM demodulation section 106 performs filtering, CP removal,DFT processing, and IFFT processing on received data received from theradio section 104, and performs DFT-S-OFDM demodulation based on radiotransmission path estimation results from the channel estimation section105.

The data demodulation section 107 demodulates received data inaccordance with downlink MCS information extracted by the control dataextraction section 108.

The control data extraction section 108 divides received data into userdata and control data (i.e., uplink data-related control information anduplink non-data-related control information), and delivers these to ahigher order layer. Note that information such as the transport blocksize and the like is included in the uplink data-related controlinformation, while information such as downlink CQI feedback informationand downlink HARQ ACK-NACK information is included in the uplinknon-data-related control information. The control data extractionsection 108 also delivers downlink MCS information from the control datato the data demodulation section 107, and delivers downlink CQIinformation to the scheduling section 109.

The scheduling section 109 is provided with a DL scheduling section109-1 which performs downlink scheduling, and a UL scheduling section109-2 which performs uplink scheduling.

Based on control information such as CQI information received by themobile station devices, information about the PRB which can be used bythe respective mobile station devices which was notified by the radioresource control section 110, the intermittent transmission andreception cycle, the PSCCH format (described below using FIG. 17), thebuffer situation and the like, the DL scheduling section 109-1 performsscheduling processing in order to map transmission data (i.e., userdata) on each channel on the downlink, and also calculates MCSinformation in order to modulate the respective data items.

Based on control information such as the result of the uplink radiotransmission path estimation which was notified by the channelestimation section 105, information about the PRU which can be used bythe respective mobile station devices which was notified by the radioresource control section 110, the intermittent transmission andreception cycle, the PSCCH format , the buffer situation and the like,the UL scheduling section 109-2 performs scheduling processing in orderfor the mobile station devices to map user data on each channel on theuplink, and also calculates MCS information in order to modulate therespective data items.

The radio resource control section 110 performs setting management forthe PSCCH format using RRC signaling between itself and the radioresource control section (i.e., the radio resource control section 203shown in FIG. 16 (described below)) of each of the mobile stationdevices. In addition, the radio resource control section 110 notifiesthe scheduling section 109 concerning control information such asinformation about PRB or PRU which can be used by the respective mobilestation devices, the intermittent transmission and reception cycle, thePSCCH format, the buffer situation and the like.

FIG. 16 is a block diagram showing the structure of the mobile stationdevice 20. The mobile station device 20 is formed so as to include atransmitting section 21, a receiving section 22, a radio section 201, ascheduling section 202, a radio resource control section 203, and aradio control section 204. The transmitting section 21 is formed so asto include a data control section 211, a data modulation section 212,and a DFT-S-OFDM modulation section 213. The receiving section 22 isformed so as to include a channel estimation section 221, an OFDMdemodulation section 222, a data demodulation section 223, and a controldata extraction section 224.

Transmission data (i.e., user data) and control data (i.e., uplinkdata-related control information and uplink non-data-related controlinformation) are input into the data control section 211. The datacontrol section 211 maps the input transmission data and control data tothe uplink PRU in accordance with instructions from the schedulingsection 202.

The data modulation section 212 performs data modulation on therespective data items input from the data control section 211 inaccordance with the coding scheme and the data modulation scheme in theMCS information instructed by the scheduling section 202.

The DFT-S-OFDM modulation section 213 performs DFT-spread OFDM signalprocessing such as serial/parallel conversion, spreading code andscrambling code multiplication processing, DFT conversion, subcarriermapping processing, IFFT processing, CP insertion, filtering and thelike on data input from the data modulation section 212, and createsDFT-spread OFDM signals. Note that schemes other than the DFT-spreadOFDM scheme can be used for the above described uplink communicationscheme and, for example, single carrier schemes such as VSCRF-CDMA, andmulti-carrier schemes such as OFDM schemes may be used.

The radio section 201 upconverts data from the DFT-S-OFDM modulationsection 213 to the radio frequency instructed by the radio controlsection 204, and transmits it using an uplink to a base station device(i.e., to the base station device 10 shown in FIG. 15). The radiosection 201 also receives downlink data from the base station device,and downconverts the received data to a baseband signal which it thendelivers to the channel estimation section 221 and the OFDM demodulationsection 222.

The channel estimation section 221 estimates radio transmission pathcharacteristics using the downlink pilot channel DPICH from the radiosection 201, and delivers the estimation result to the OFDM demodulationsection 222. The channel estimation section 221 also converts the radiotransmission path estimation result to CQI information, and deliversthis CQI information to the data control section 211 and the schedulingsection 202. Note that the CQI information is used in order to thenotify the base station device about the radio transmission pathestimation result.

The OFDM demodulation section 222 performs OFDM signal processing suchas CP removal, filtering, and FFT processing and the like on datareceived from the radio section 201, and performs OFDM demodulationbased on the radio transmission path estimation result from the channelestimation section 221.

The data demodulation section 223 demodulates received data inaccordance with the downlink MCS information extracted by the controldata extraction section 224.

The control data extraction section 224 separates the received data intouser data (for the downlink shared data channel PDSCH) and control data(for the downlink shared control channel PSCCH). The control dataextraction section 224 also delivers the downlink MCS information fromthe separated control data to the data demodulation section 223, anddelivers uplink MCS information and scheduling information to thescheduling section 202.

The scheduling section 202 issues commands to the data control section211, the data modulation section 212, and the DFT-S-OFDM modulationsection 213 in accordance with the uplink MCS information and schedulinginformation received from the base station device in order for thetransmission data and control data to be mapped to a physical channel.

The radio resource control section 203 manages information about usablePRB or PRU, the intermittent transmission and reception cycle, and thePSCCH format and the like, and delivers these respective managementinformation items to the transmitting section 21, the receiving section22, the scheduling section 202, and the radio control section 204 so asto perform the overall control of the mobile station device 20.

4. Operations of the Base Station and Mobile Stations

Next, a description will be given using FIGS. 17 through 19 of theoperations of the above described base station and mobile stations.

FIG. 17 is a sequence diagram showing a procedure performed by a basestation to set a PSCCH format in a mobile station. The PSCCH format isformed by information indicating whether the mobile station will use adynamic format or a semi-static format, and setting information for boththe dynamic format and semi-static format. Included in the settinginformation for the semi-static format are information showing theformat allocated to the mobile station, information showing the groupingwithin the format allocated to the mobile station, identificationinformation for the format or group within a format, information showinga relationship between the format and the physical placement of thedownlink shared control channel PSCCH, information showing arelationship between the group within the format and the physicalplacement of the downlink shared control channel PSCCH, informationshowing a relationship between the group within the format and theusable PRB or PRU, the Short UEID which can be used by the group withinthe format, information indicating which control information is to beused for the LTFS, and the like. The mobile station identificationinformation C-RNTI is included in the setting information for thedynamic format.

In FIG. 17, the base station uses RRC signaling to transmit a PSCCHformat setting signal to the mobile station when communication with themobile station begins (i.e., for radio bearer setup, during signaltransmission, or during signal reception) or when there is an alterationto the control signal format during communication with the mobilestation (step S101 and step S102). The mobile station receives the PSCCHformat setting signal transmitted from the base station, holds thatPSCCH format, and performs the next and subsequent communications (i.e.,transmissions and receptions of the downlink shared data channel PDSCHand the uplink shared data channel PUSCH, and the reception of controlinformation using the downlink shared control channel PDSCH) inaccordance with the relevant PSCCH format (step S103). The base stationalso holds the PSCCH format transmitted to the respective mobilestations, and performs the next and subsequent communications with therespective mobile stations in accordance with the relevant PSCCH format(step S104).

FIG. 18 is a flowchart showing the processing performed by a basestation in 1TTI.

In each TTI, the base station detects mobile stations for whichscheduling is possible based on the PSCCH format setting (step S201),and selects high priority mobile stations from among the detectedscheduling-capable mobile stations (step S202). This prioritydetermination is made on the basis of transmission path situation ofeach mobile station, the buffer situation, the service class, and theQoS (Quality of Service) and the like. Next, the base station determinesthe PRB or PRU allocated to the selected mobile stations and performsfrequency scheduling (step S203). The base station then transmitscontrol information (C-RNTI, Cat2, Cat3) by means of the downlink sharedcontrol channel PSCCH to dynamic format mobile stations from among theselected mobile stations, and transmits a format ID (or group ID) andLTFS to semi-static format mobile stations from among the selectedmobile stations (step S204). Next, the base station places the downlinkshared data channel PDSCH addressed to the relevant mobile station inthe PRB specified by the downlink shared control channel PSCCHtransmitted to the mobile station, and then transmits user data (stepS205). Thereafter, it moves to the next TTI (step S206).

Note that when the base station is placing the downlink shared datachannel PDSCH, it makes this placement based on information showing theformat allocated to the mobile station, information showing the groupingwithin the format allocated to the mobile station, identificationinformation for the format or group within a format, information showinga relationship between the format and the physical placement of thedownlink shared control channel PSCCH, the relationship between thegroup within the format and the physical placement of the downlinkshared control channel PSCCH, the relationship between the group withinthe format and the usable PRB group, and the Short UEID grouping whichcan be used by the group within the format.

FIG. 19 is a flowchart showing the processing performed by a mobilestation in 1TTI.

In each TTI, in accordance with the PSCCH format settings (once thereception of step S103 of FIG. 17 has ended), the mobile stationspecifies the C-RNTI or format ID (or group ID) to be detected based onwhether or not a PRB or PRU which it is able to use is included therein,and on the physical placement of the downlink shared control channelPSCCH which it should be detecting, and on the information string whichshould be included in the CRC area of the downlink shared controlchannel PSCCH, and the like (step S301). If a usable PRB or PRU is notincluded therein, processing is ended in that TTI.

If a usable PRB or PRU is included therein, the mobile station receivesthe downlink shared control channel PSCCH (step S302), and when its ownC-RNTI or format ID (or group ID) has been detected in the CRC check(step S303), it performs analysis on the data within the downlink sharedcontrol channel PSCCH in accordance with the PSCCH format (step S304).Here, in the case of a semi-static format, the mobile station interpretsthe detected format ID (or group ID) and the format which is determinedby the PSCCH format, and obtains the Short UEID and LTFS. After themobile station has analyzed the data within the downlink shared controlchannel PSCCH, it performs transmission and reception of the downlinkshared data channel PDSCH and the uplink shared data channel PUSCH inaccordance with the specified modulation scheme and coding scheme andthe like (step S306). In the format in which the Short UEID is included,if the mobile station is unable to detect its own Short UEID, theprocessing of this downlink shared control channel PSCCH is ended.

In contrast, if the mobile station is unable to detect its own C-RNTI inthe CRC check in step S303, the mobile station determines whether or notit has checked all the downlink shared control channels PSCCH which itshould have checked in accordance with the PSCCH format (step S305), andif it has checked all the downlink shared control channels PSCCH, thenthe processing in this TTI is ended. If it has not checked all thedownlink shared control channels PSCCH, it updates the downlink sharedcontrol channels PSCCH which need to be detected (step S308), and onceagain performs the downlink shared control channel PSCCH detectionprocessing.

An embodiment of this invention has been described in detail above withreference made to the drawings, however, the specific structure thereofis not limited to this and various design modifications and the like arepossible insofar as they do not depart from the spirit or scope of thisinvention.

The program which is operated by the base station device and mobilestation devices according to the present invention is a program whichcontrols a CPU or the like (i.e., a program which causes a computer tofunction) so as to achieve the functions of the above describedembodiment of the present invention. In addition, information handled bythese devices is temporarily stored in RAM during the above describedprocessing, and is thereafter stored in ROM or on a HDD or the likewhere it can be read, modified, or rewritten when required by the CPU.

The recording medium which stores this program maybe any one of asemiconductor medium (for example, ROM or a nonvolatile memory card orthe like), an optical recording medium (for example, a DVD, MO, MD, CD,BD, or the like), or a magnetic recording medium (for example, magnetictape or a flexible disk or the like), or the like.

Moreover, not only is it possible for the functions of the abovedescribed embodiment to be implemented by executing the loaded program,but the functions of the present invention may also be implemented byperforming this processing in conjunction with an operating system oranother application program or the like based on commands from thisprogram.

When this product is distributed to the marketplace, the program can bestored on a portable recording medium and distributed, or it can betransferred to a server computer which is connected via a network suchas the Internet or the like. In this case, the recording device of theserver computer also functions as the recording medium of the presentinvention.

INDUSTRIAL APPLICABILITY

It is possible to transmit and receive control information efficientlyin a radio system.

What is claimed is:
 1. A mobile station device, comprising: a receiverconfigured to receivecontrol information from a base stationdevicethrough a control information channel, the control informationcomprising a cyclic redundancy check (CRC) field and a payload field,and receive, from the base station device, information specifying a partof the payload field in which a control information item to be used bythe mobile station device is placed; and a processor configured toacquire the control information item based on a format of the payloadfield and the information specifying a part of the payload field;wherein bits of the CRC field are masked by an identificationinformation identifyingthe format of the payload field, the formatspecifying types of control information items included in the payloadfield, sizes of the control information itemsin bits, andpositions ofthe control information itemswithin the payload field.
 2. The mobilestation deviceaccording to claim 1, whereinthe control informationincludes at least one of downlink control information includingapositionof a physical resource block (PRB) where data addressed to themobile station device is placed, modulation scheme, data length, andinformation required for hybrid automatic repeat request (HARQ).
 3. Themobile station deviceaccording to claim 1, whereinthe controlinformation includes at least one of uplink control informationincludinga position of a physical resource block (PRB) to which themobile station device transmit data, modulation scheme, data length,transmission timing control, power control, and a HARQ acknowledgement(ACK)/ non-acknowledgement (NACK) for the data transmitted by the mobilestation device.
 4. A control information reception method, comprising:receiving,by a mobile station device, control information from a basestation device through a control information channel, the controlinformation comprising a cyclic redundancy check (CRC) field and apayload field; receiving, by the mobile station device, from the basestation device, information specifying a part of the payload field inwhich a control information item to be used by the mobile stationdeviceis placed; and acquiring, by the mobile station device, thecontrol information item based on a format of the payload field and theinformation specifying a part of the payload field; wherein bits of theCRC field are masked by an identification information identifying theformat of the payload field, the format specifying types of controlinformation items included in the payload field, sizes of the controlinformation items in bits, andpositions of the control information itemswithin the payload field.
 5. The method according to claim 4, whereinthecontrol information includes at least one of downlink controlinformation including a position of a physical resource block (PRB)where data addressed to the mobile station device is placed, modulationscheme, data length, and information required for hybrid automaticrepeat request (HARQ).
 6. The method according to claim 4, whereinthecontrol information includes at least one of uplink control informationincludinga position of a physical resource block (PRB) to which themobile station device transmit data, modulation scheme, data length,transmission timing control, power control, and a HARQ acknowledgement(ACK)/non-acknowledgement (NACK) for the data transmitted by the mobilestation device.